In ducts, for example, molded foam provided with a flange portion for connecting to another tubular member in the vicinity of an opening of the tube body is widely used.
In particular, as for a duct for allowing the air from an air conditioner to breeze, a light-weight duct having excellent thermal insulating properties can be achieved by using a tubular molded foam. Further, in such a duct using the tubular molded foam, the thermal insulating properties and light-weight of the duct can be further improved by increasing the expansion ratio during manufacturing to increase the number of foams within the foam. Accordingly, the use of the tubular molded foam is more effective.
As a method for manufacturing the molded foam, a method of forming a molded foam by clamping a molten resin with a split mold block is well known. In recent years, mass production of tubular foam having an improved expansion ratio is becoming possible along with the improvement in molding techniques.
Additionally, as a technique for which an application was previously filed by the applicant of this application, there is a technique for manufacturing a molded product having a tubular portion and a plate portion, by clamping a resin sheet formed of foamed resin and a resin sheet formed of solid resin with a split mold block (for example, see Patent Literature 1).
Patent Literature 1: Japanese Patent Application Laid-Open No. 2011-131776